Convertible Preferred Stock (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Equity [Abstract]

Schedule of Shares of Convertible Preferred Stock and Common Stock

The changes in the shares of convertible preferred stock and common stock during the years ended December 31, 2013 and 2014 were as follows:

	Series A Convertible Preferred Stock			Extinguished Series B-1 Convertible Preferred Stock			Extinguished Series C Convertible Preferred Stock			Extinguished Series D-1 Convertible Preferred Stock			Extinguished Series D-2 Convertible Preferred Stock			New Series B Convertible Preferred Stock		New Series C Convertible Preferred Stock		Total Convertible Preferred Stock			Common Stock
Balance at December 31, 2012		163,462			6,321,238			9,108,533			1,155,172			—			—		—		16,748,405			730,203
Issuance of Series D-1 convertible preferred stock		—			—			—			983,558			—			—		—		983,558			—
Issuance of Series D-2 convertible preferred stock		—			—			—			—			3,013,797			—		—		3,013,797			—
Conversion of Series C convertible preferred stock and related dividends into common stock and deemed capital contribution		—			—			(1,470,485	)		—			—			—		—		(1,470,485	)		147,051
Conversion of accrued dividends into Series D-2 convertible preferred stock		—			—			—			—			3,196,417			—		—		3,196,417			—
Extinguishment of Series B-1, Series C, Series D-1 and Series D-2 convertible preferred stock		—			(6,321,238	)		(7,638,048	)		(2,138,730	)		(6,210,214	)		—		—		(22,308,230	)		—
Exchange of new Series B convertible preferred stock and deemed dividend		—			—			—			—			—			22,308,230		—		22,308,230			—
Issuance of new Series C convertible preferred stock		—			—			—			—			—			—		2,564,638		2,564,638			—
Issuance of common stock from option exercises		—			—			—			—			—			—		—		—			1,463
Balance at December 31, 2013		163,462			—			—			—			—			22,308,230		2,564,638		25,036,330			878,717
Repurchase of Series A convertible preferred stock and deemed capital contribution		(1,353	)		—			—			—			—			—		—		(1,353	)		—
Issuance of Series C convertible preferred stock		—			—			—			—			—			—		880,546		880,546			—
Conversion of convertible promissory notes into Series C convertible preferred stock		—			—			—			—			—			—		1,739,405		1,739,405			—
Issuance of common stock from option exercises		—			—			—			—			—			—		—		—			28,320
Balance at December 31, 2014		162,109			—			—			—			—			22,308,230		5,184,589		27,654,928			907,037

Components of Convertible Preferred Stock

Convertible preferred stock as of September 30, 2015 and December 31, 2014 consisted of the following (in thousands, except share data):

	September 30, 2015
	Shares Authorized		Shares Issued and Outstanding		Aggregate Liquidation Preference		Net Carrying Value
	(Unaudited)
Series A		398,500		—	$	—	$	—
Series B		60,500,000		—		—		—
Series C		19,812,497		—		—		—
Total		80,710,997		—	$	—	$	—

	December 31, 2014
	Shares Authorized		Shares Issued and Outstanding		Aggregate Liquidation Preference		Net Carrying Value
Series A		398,500		162,109	$	3,004	$	3,003
Series B		60,500,000		22,308,230		113,405		112,080
Series C		13,562,497		5,184,589		30,323		30,027
Total		74,460,997		27,654,928	$	146,732	$	145,110

Convertible preferred stock at December 31, 2013 and 2014 consisted of the following (in thousands, except share data):

	December 31, 2013
	Shares Authorized		Shares Issued and Outstanding		Aggregate Liquidation Preference		Net Carrying Value
Series A		398,500		163,462	$	3,029	$	3,028
Series B		60,500,000		22,308,230		113,405		112,080
Series C		6,562,497		2,564,638		15,000		14,929
		67,460,997		25,036,330	$	131,434	$	130,037

	December 31, 2014
	Shares Authorized		Shares Issued and Outstanding		Aggregate Liquidation Preference		Net Carrying Value
Series A		398,500		162,109	$	3,004	$	3,003
Series B		60,500,000		22,308,230		113,405		112,080
Series C		13,562,497		5,184,589		30,323		30,027
		74,460,997		27,654,928	$	146,732	$	145,110